Investigation opens after a fish kill at Guana Preserve

An investigation is underway after a fish kill at Guana Preserve in Ponte Vedra Beach. News4JAX reported Sept. 25, 2026, that fishermen say the kill took hundreds of trophy-sized trout, redfish, and other popular species.

St. Johns County Commissioner Clay Murphy told the station he met with the Florida Department of Environmental Protection and Guana Preserve officials after visiting the preserve on Thursday. Weather kept the group off the airboat, so water samples are planned for next week. Murphy said those officials’ concern was a spike in bacteria they described as unusual. Environmentalists told News4JAX that a bacterial spike may have contributed to the kill. Murphy said the county still needs more evidence before naming a cause. He listed possibilities the county is looking at together: lawn fertilizer, other human activity, cattle, illegal dumping, or a natural event. Officials also plan to work with the St. Johns County Sheriff’s Office, look at nearby canals, sample specific parts of the estuary, and map every waterway that feeds the Guana River system.

Captain Matt Chipperfield, a local fishing guide and environmentalist, told News4JAX that stormwater runoff from nearby communities may be carrying pollutants into the preserve, and that the primary path for that runoff is through the Sawgrass community. He said storm drains, canals, ponds, golf courses, and lawns feed rivers and canals that eventually reach a non-tidal lagoon in the preserve, where algae can feed on built-up nutrients. Chipperfield said a recent DEP study showed a significant increase in pollution over the past six years. Environmentalists are preparing a water-restoration proposal. News4JAX reported that much of the testing is already underway, and that environmentalists working with DEP expect to bring a restoration plan to the St. Johns County Commission in October or November.

Photo: News4JAX — dead fish along the Guana Preserve shoreline, from the station’s Sept. 25, 2026 report.

This is a The Gillnet news desk summary, not a reprint.

Source: News4JAX — Investigation underway after hundreds of trophy-sized fish die at Guana Preserve (Tarik Minor, published Sept. 25, 2026).